The benefits and properties of glycyrrhetinic acid on the skin.

Glycyrrhetinic acid, also known as enoxolone, is recognised for its anti-inflammatory properties and aids in diminishing redness and alleviating itching. Ideal for sensitive or atopic skin, this active ingredient is incorporated into the formulation of numerous soothing skincare products. Several studies have investigated the mode of action of glycyrrhetinic acid, revealing that this active ingredient operates at various levels to reduce inflammation.

Researchers initially established that glycyrrhetinic acid could affect the glucocorticoid receptor and prevent it from interacting with the Nf-kB transcription factor, involved in immune and inflammatory responses. It was also demonstrated that glycyrrhetinic acid inhibited the activity of TNF-α and interleukin-1α, pro-inflammatory cytokines. These are involved in a series of reactions leading to redness and itching. Finally, glycyrrhetinic acid is capable of inhibiting the production of leukotrienes, lipid mediators playing a major role in immunity and inflammation.

Glycyrrhetinic acid is also found in many brightening products or those targeting issues ofhyperpigmentation. Brown spots appear when melanin, the pigment that gives skin its colour, is overproduced in certain areas of the body. There are three types of pigmented spots: melasma or pregnancy mask, related to hormonal imbalances, the solar lentigo or sun spots, due to excessive and repeated UV exposure, and post-inflammatory hyperpigmentation which results from an overproduction of melanin following inflammation (injuries, burns, acne outbreaks...).

The application of a treatment based on glycyrrhetinic acid can help to diminish these marks. Indeed, this active ingredient possesses properties of melanin dispersion and a study has shown that it inhibits tyrosinase, the key enzyme in the melanogenesis process, when it is present at concentrations higher than 0.5%.

Note : The lightening property of glycyrrhetinic acid is a subject of debate. Indeed, some studies conclude that this active ingredient actually has a stimulating effect on melanogenesis. Therefore, caution should be exercised.

Studies have shown that enoxolone has bactericidal effects against Staphylococcus aureus. Its mechanism of action has not yet been fully elucidated, but it is hypothesised that this active ingredient disrupts the integrity of the bacterial membrane, leading to leakage of essential cellular components and the death of the bacteria. Glycyrrhetinic acid can thus contribute to the control of bacterial populations living on our skin.

UV rays, pollution, smoking... are all factors that generate oxidative stress in the skin cells. Oxidative stress is referred to when there is an imbalance between the number of antioxidants and free radicals. These free radicals damage cells, DNA, and proteins and are responsible for several skin discomforts (hyperpigmentation, premature ageing, melanomas...). Antioxidants can neutralise free radicals, which is why it is recommended to incorporate them into your skincare routine.

With regards to glycyrrhetinic acid, it functions by increasing the expression of theheme oxygenase HO-1, an antioxidant enzyme. It has also been demonstrated that it can inhibit lipid peroxidation, a chain reaction leading to the damage of cell membranes and the disruption of the hydrolipidic film. Therefore, glycyrrhetinic acid has a protective effect against damage induced by free radicals.

To a certain extent, enoxolone can delay skin ageing. It helps to prevent skin sagging and the appearance of wrinkles. Glycyrrhetinic acid is indeed capable of inhibiting the activity of MMP-1 and MMP-3, which are matrix metalloproteinases. These are proteases involved in the modification of the extracellular matrix. MMP-1 are collagenases, enzymes that act by breaking the peptide bonds of collagen. In doing so, they cause the loss of structure and therefore function of this molecule essential to the skin's suppleness. MMP-3 refers to stromelysins, enzymes that play a minor role in the degradation of the extracellular matrix but whose overexpression is associated with the development of cancerous cells. Therefore, it can be cautiously considered that in addition to slowing down skin ageing, glycyrrhetinic acid has a protective effect on skin cells.

• Document du fournisseur.

• HOSSEINZADEH H. & al. Review of pharmacological effects of Glycyrrhiza sp. and its bioactive compounds. Phytotherapy Research (2008).

• KALINOWSKA-LIS U. & al. 18β-Glycyrrhetinic acid: its core biological properties and dermatological applications. International Journal of Cosmetic Science (2019).